<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        function changCode(){
            var imgObj=document.getElementById("changCode");
            imgObj.src="/checkCode?"+Math.random();
        }
    </script>
</head>
<body>
<form action="user/land" method="post">
    用户名： <input type="text" name="username"><br>
    密码：<input type="text" name="password"><br>
    <img src="/checkCode" id="changCode"><a href="javascript:changCode()">看不起换一张</a>><br>
    验证码：<input type="text" name="userCore"><br>
    <input type="submit" value="提交">
</form>

</body>
</html>